It is now possible to simulate condensed media using computers. Two techniques used are molecular dynamics simulations and Monte Carlo simulations. Both of these techniques will be used to study the structural, thermodynamic and transport properties of aqueous solutions. Our quest is to understand "hydrophobic solvation" and the "hydrophobic interaction" and the role it plays in producing different states of aggregation (as in micelles and bilipid membranes) and in chemical reactions involving conformational changes of dissolved molecules. The first part of this proposal concerns a detailed study of how the water structure changes as we vary the conformation of simple hydrocarbons. This will give the intramolecular potential of mean force and will tell how chain molecules fold in aqueous solution. The second part of this proposal involves a study of the dynamics of conformation changes. The third part of the proposal involves a study of the aggregation of long chain carboxylic acids. Here we would like to study the structure of dimers and later, possibly, the size and structure of micelles. The fourth part of this propsal involved the study of solvent effects on quantum molecular internal degrees of freedom and their attendant spectra. This study will progress in stages from the simple to the complex. It will involve novel simulation techniques invented in our laboratory. It should lead to an understanding of the basic hydrophobic interactions implicated in biochemical reactions.